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<div class="titlepage"><div><div><h5 class="title">
<a name="spirit.karma.performance_measurements.numeric_performance.int_performance"></a><a class="link" href="int_performance.html" title="Comparing the performance of a single int_ generator">Comparing
          the performance of a single int_ generator</a>
</h5></div></div></div>
<p>
            These performance measurements are centered around default formatting
            of a single <code class="computeroutput"><span class="keyword">int</span></code> integer
            number using different libraries and methods. The overall execution times
            for those examples are compared below. We compare using <code class="computeroutput"><span class="identifier">sprintf</span></code>, C++ iostreams, <a href="../../../../../../../../libs/format/index.html" target="_top">Boost.Format</a>,
            and <span class="emphasis"><em>Spirit.Karma</em></span>.
          </p>
<p>
            For the full source code of the performance test please see here: <a href="../../../../../../workbench/karma/int_generator.cpp" target="_top">int_generator.cpp</a>.
            All the measurements have been done by executing <code class="computeroutput"><span class="number">1e7</span></code>
            iterations for each formatting type (NUMITERATIONS is set to <code class="computeroutput"><span class="number">1e7</span></code> in the code shown below).
          </p>
<p>
            Code used to measure the performance for <code class="computeroutput"><span class="identifier">ltoa</span></code>:
          </p>
<p>
</p>
<pre class="programlisting"><span class="keyword">char</span> <span class="identifier">buffer</span><span class="special">[</span><span class="number">65</span><span class="special">];</span> <span class="comment">// we don't expect more than 64 bytes to be generated here</span>
<span class="keyword">for</span> <span class="special">(</span><span class="keyword">int</span> <span class="identifier">i</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span> <span class="identifier">i</span> <span class="special">&lt;</span> <span class="identifier">MAX_ITERATION</span><span class="special">;</span> <span class="special">++</span><span class="identifier">i</span><span class="special">)</span>
<span class="special">{</span>
    <span class="identifier">ltoa</span><span class="special">(</span><span class="identifier">v</span><span class="special">[</span><span class="identifier">i</span><span class="special">],</span> <span class="identifier">buffer</span><span class="special">,</span> <span class="number">10</span><span class="special">);</span>
<span class="special">}</span>
</pre>
<p>
          </p>
<p>
            Code used to measure the performance for standard C++ iostreams:
          </p>
<p>
</p>
<pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">stringstream</span> <span class="identifier">str</span><span class="special">;</span>
<span class="keyword">for</span> <span class="special">(</span><span class="keyword">int</span> <span class="identifier">i</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span> <span class="identifier">i</span> <span class="special">&lt;</span> <span class="identifier">MAX_ITERATION</span><span class="special">;</span> <span class="special">++</span><span class="identifier">i</span><span class="special">)</span>
<span class="special">{</span>
    <span class="identifier">str</span><span class="special">.</span><span class="identifier">str</span><span class="special">(</span><span class="string">""</span><span class="special">);</span>
    <span class="identifier">str</span> <span class="special">&lt;&lt;</span> <span class="identifier">v</span><span class="special">[</span><span class="identifier">i</span><span class="special">];</span>
<span class="special">}</span>
</pre>
<p>
          </p>
<p>
            Code used to measure the performance for <a href="../../../../../../../../libs/format/index.html" target="_top">Boost.Format</a>:
          </p>
<p>
</p>
<pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">str</span><span class="special">;</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">format</span> <span class="identifier">int_format</span><span class="special">(</span><span class="string">"%d"</span><span class="special">);</span>
<span class="keyword">for</span> <span class="special">(</span><span class="keyword">int</span> <span class="identifier">i</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span> <span class="identifier">i</span> <span class="special">&lt;</span> <span class="identifier">MAX_ITERATION</span><span class="special">;</span> <span class="special">++</span><span class="identifier">i</span><span class="special">)</span>
<span class="special">{</span>
    <span class="identifier">str</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">str</span><span class="special">(</span><span class="identifier">int_format</span> <span class="special">%</span> <span class="identifier">v</span><span class="special">[</span><span class="identifier">i</span><span class="special">]);</span>
<span class="special">}</span>
</pre>
<p>
          </p>
<p>
            Code used to measure the performance for <span class="emphasis"><em>Spirit.Karma</em></span>
            using a plain character buffer:
          </p>
<p>
</p>
<pre class="programlisting"><span class="keyword">char</span> <span class="identifier">buffer</span><span class="special">[</span><span class="number">65</span><span class="special">];</span> <span class="comment">// we don't expect more than 64 bytes to be generated here</span>
<span class="keyword">for</span> <span class="special">(</span><span class="keyword">int</span> <span class="identifier">i</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span> <span class="identifier">i</span> <span class="special">&lt;</span> <span class="identifier">MAX_ITERATION</span><span class="special">;</span> <span class="special">++</span><span class="identifier">i</span><span class="special">)</span>
<span class="special">{</span>
    <span class="keyword">char</span> <span class="special">*</span><span class="identifier">ptr</span> <span class="special">=</span> <span class="identifier">buffer</span><span class="special">;</span>
    <span class="identifier">karma</span><span class="special">::</span><span class="identifier">generate</span><span class="special">(</span><span class="identifier">ptr</span><span class="special">,</span> <span class="identifier">int_</span><span class="special">,</span> <span class="identifier">v</span><span class="special">[</span><span class="identifier">i</span><span class="special">]);</span>
    <span class="special">*</span><span class="identifier">ptr</span> <span class="special">=</span> <span class="char">'\0'</span><span class="special">;</span>
<span class="special">}</span>
</pre>
<p>
          </p>
<p>
            The following table shows the overall performance results collected while
            using different compilers. All times are in seconds measured for <code class="computeroutput"><span class="number">1e7</span></code> iterations (platform: Windows7, Intel
            Core Duo(tm) Processor, 2.8GHz, 4GByte RAM). For a more readable comparison
            of the results see this <a class="link" href="int_performance.html#spirit.karma.int_performance" title="Figure 3. Performance comparison for a single int">figure</a>.
          </p>
<div class="table">
<a name="spirit.karma.performance_measurements.numeric_performance.int_performance.performance_comparison_for_a_single_int__all_times_in__s____1e7__iterations_"></a><p class="title"><b>Table 5. Performance comparison for a single int (all times in [s], `1e7`
            iterations)</b></p>
<div class="table-contents"><table class="table" summary="Performance comparison for a single int (all times in [s], `1e7`
            iterations)">
<colgroup>
<col>
<col>
<col>
<col>
<col>
<col>
<col>
</colgroup>
<thead><tr>
<th>
                    <p>
                      Library
                    </p>
                  </th>
<th>
                    <p>
                      gcc 4.4.0 (32 bit)
                    </p>
                  </th>
<th>
                    <p>
                      VC++ 10 (32 bit)
                    </p>
                  </th>
<th>
                    <p>
                      Intel 11.1 (32 bit)
                    </p>
                  </th>
<th>
                    <p>
                      gcc 4.4.0 (64 bit)
                    </p>
                  </th>
<th>
                    <p>
                      VC++ 10 (64 bit)
                    </p>
                  </th>
<th>
                    <p>
                      Intel 11.1 (64 bit)
                    </p>
                  </th>
</tr></thead>
<tbody>
<tr>
<td>
                    <p>
                      ltoa
                    </p>
                  </td>
<td>
                    <p>
                      1.542
                    </p>
                  </td>
<td>
                    <p>
                      0.895
                    </p>
                  </td>
<td>
                    <p>
                      0.884
                    </p>
                  </td>
<td>
                    <p>
                      1.163
                    </p>
                  </td>
<td>
                    <p>
                      1.099
                    </p>
                  </td>
<td>
                    <p>
                      0.906
                    </p>
                  </td>
</tr>
<tr>
<td>
                    <p>
                      iostreams
                    </p>
                  </td>
<td>
                    <p>
                      6.548
                    </p>
                  </td>
<td>
                    <p>
                      13.727
                    </p>
                  </td>
<td>
                    <p>
                      11.898
                    </p>
                  </td>
<td>
                    <p>
                      3.464
                    </p>
                  </td>
<td>
                    <p>
                      8.316
                    </p>
                  </td>
<td>
                    <p>
                      8.115
                    </p>
                  </td>
</tr>
<tr>
<td>
                    <p>
                      <a href="../../../../../../../../libs/format/index.html" target="_top">Boost.Format</a>
                    </p>
                  </td>
<td>
                    <p>
                      16.998
                    </p>
                  </td>
<td>
                    <p>
                      21.813
                    </p>
                  </td>
<td>
                    <p>
                      20.477
                    </p>
                  </td>
<td>
                    <p>
                      17.464
                    </p>
                  </td>
<td>
                    <p>
                      14.662
                    </p>
                  </td>
<td>
                    <p>
                      13.646
                    </p>
                  </td>
</tr>
<tr>
<td>
                    <p>
                      <span class="emphasis"><em>Spirit.Karma</em></span> int_
                    </p>
                  </td>
<td>
                    <p>
                      1.421
                    </p>
                  </td>
<td>
                    <p>
                      0.744
                    </p>
                  </td>
<td>
                    <p>
                      0.697
                    </p>
                  </td>
<td>
                    <p>
                      1.072
                    </p>
                  </td>
<td>
                    <p>
                      0.953
                    </p>
                  </td>
<td>
                    <p>
                      0.606
                    </p>
                  </td>
</tr>
</tbody>
</table></div>
</div>
<br class="table-break"><p>
            </p>
<div class="figure">
<a name="spirit.karma.int_performance"></a><p class="title"><b>Figure 3. Performance comparison for a single int</b></p>
<div class="figure-contents"><span class="inlinemediaobject"><img src="../../../.././images/int_performance.png" alt="Performance comparison for a single int"></span></div>
</div>
<p><br class="figure-break">
          </p>
</div>
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<td align="right"><div class="copyright-footer">Copyright © 2001-2011 Joel de Guzman, Hartmut Kaiser<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
      </p>
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